Apparatus and methods for transporting and processing substrates

ABSTRACT

There is described apparatus and methods for transporting and processing substrates including wafers as to efficiently produce at reasonable costs improved throughput as compared to systems in use today. A key element is the use of a transport chamber along the sides of processing chambers for feeding substrates into a controlled atmosphere through a load lock and then along a transport chamber as a way of reaching processing chambers and then out of the controlled atmosphere following processing in the processing chambers.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.11/523,101, filed Sep. 19, 2006, the disclosure of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

This invention has to do with novel apparatus and methods fortransporting and processing substrates in general and wafers inparticular.

BACKGROUND

In the manufacture of semiconductors, a common tool, referred to as acluster tool, is one of the key units used in the manufacture of wafers.A typical commercial device has a generally circular central area withchambers attached along the circumference. The chambers extend outwardaround the central area. When wafers are processed they are moved firstfrom an input output station on the circumference of the central chamberinto the central chamber and then from the central chamber into anattached or circumferential chamber where processing is performed. Inthis tool as in substantially all manufacturing systems used today, thepractice is to process wafers one at a time. A wafer may be moved into achamber for processing and then back to the central chamber. This can befollowed by a further move to another circumferential chamber and thenfollowing processing, back to the central chamber. Eventually the waferwhen fully processed is moved out of the tool altogether. The movementout goes again through an input/output station or chamber which inconnection with vacuum systems is generally called a load lock where thewafer moves from vacuum to atmosphere. A unit of this sort is describedfor example in U.S. Pat. No. 4,951,601.

Another tool indexes wafers along a central axis and feeds wafersthrough surrounding processing chambers. In this tool, all wafers arefed simultaneously to the next processing stop. Wafers cannot moveindependently although they can be processed independently. They allremain at a process station for the same amount of time but theprocesses at each station can be independently controlled subject ofcourse to the maximum time permitted by the time permitted for the stop.Although the first described tool could be made to operate in this way,in fact however, it may move wafers so that they do not progress to theadjacent processing chamber in sequence and all are not required to havethe same dwell time at a processing chamber.

When either of these systems is operating the central area is generallyat vacuum but it may also be at some other preselected or predeterminedand controlled environment. This central section for example can havepresented a gas that is useful to the processes being preformed in theprocess chambers. The chambers or compartments along the outer surfaceof the central zone are generally at a vacuum too but may also have apre-selected and controlled gaseous environment. Processing is alsogenerally performed in a vacuum by moving wafers while in vacuum fromthe central chamber to an attached chamber or compartment. Generallyonce the wafer reaches a chamber or compartment for processing, thechamber or compartment is sealed off from the central chamber. Thisprevents materials and/or gases used in the processing chamber orcompartment from reaching the central zone preventing contamination ofthe atmosphere in the central zone as well as attached processingchambers and/or preventing contamination of wafers located in thecentral zone waiting to be processed or further processed. This alsopermits the processing chamber to be set at a vacuum level differentthan that used in the central chamber for the particular processing tobe carried out in the chamber. For example, if the processing technologyof a chamber requires more of a vacuum, then with a seal in placebetween the central zone and the chamber, the chamber itself can befurther pumped down to match the process requirements for the particularprocesses to be performed within that chamber. Alternatively, if less ofa vacuum is required, the pressure may be increased without affectingthe pressure of the central chamber. After processing of the wafer iscompleted, the wafer is moved back to the central chamber and then outof the system. In this way the wafer may progress through this toolsequentially through the chambers and all of the available processes.Alternatively the wafer may proceed through only selected chambers andbe exposed to only selected processes.

Variations on these processes are also in use in equipment offered tothe field. However, they all tend to rely on a central area or zone thatis integral to the various processes. Also since the predominant usageof such equipment is to make wafers, the discussion will primarily be interms of wafers. However, it should be understood that most of theprocesses under discussion are also applicable to substrates in generaland that the discussions should be taken to also apply to suchsubstrates and such manufacturing equipment.

Recently there has been described a system that is distinct from these,in that it is linear in shape rather than circular and wafers move forprocessing from one chamber to the next chamber. Since the wafer movesin sequence from one chamber to an adjacent chamber, there is no needfor the central zone as part of the equipment. In this tool a waferenters the unit and is generally attached to a chuck that travels withthe wafer as it moves through the system. In this unit, processing isperformed for equal amounts of time in each chamber.

This system has a smaller footprint than is typical in this field sincethe footprint approximates the footprint of the processing chambers onlyand does not include a large central zone. This is an advantage of thistype equipment. This system is described in a pending published patentapplication, Publication No. 2006/0102078 A1. This particular system hasa uniform dwell time at each process station. This allows for somedifferences in processing limited of course by the length of the longestdwell period. If one requires independently controlled dwell times atthe various stations, another approach may be preferred. Also this typeof equipment has the disadvantage that if one station is down for repairor maintenance, then the whole system is itself unavailable forprocessing.

SUMMARY OF THE INVENTION

This invention is directed to a novel wafer processing unit intended topermit separately controlled dwell times at processing stations whilemaintaining a small footprint. It also allows ongoing operations even ifone or more of the stations is down for one reason or another. In partthis is in recognition that the cost of manufacturing semiconductors isextremely high and costs are increasing. The higher the costs thegreater the risks in undertaking investments in this field. An objectiveis to define equipment that lowers costs by a reasonable percentage andprovides improved systems and services in accordance with “Lean”principles of manufacture. Thus an objective is to maximize processingchambers while maintaining a small footprint. Another objective is tomaximize process station utilization. Another objective is to simplifyrobotics and the service of this equipment. The system will also offerconsiderable redundancy, including up to 100% availability of the systemfor processing even during mainframe servicing. In such an event lesschambers will be in use but all processes can continue to be availablefor treatment of wafers. And servicing or processing chambers will bepossible from the back or front of the processing chambers.Additionally, in the preferred embodiment the processing chambers willbe set up in a linear arrangement. This assures the smallest footprintfor a system that permits individual programs for wafers at the variousprocessing stations.

The processing chambers generally may have the capability of performingany of the various processes one uses in connection with processingwafers. For example in the manufacture of a wafer, the wafer wouldnormally be carried through one or more etching steps, one or moresputtering or physical vapor deposition processes, ion implantation,chemical vapor deposition (CVD) and heating and/or cooling processes,among others. The number of processing steps to make a wafer could meanthat multiple tools or tools with large subsystems would have beenrequired if using prior art devices to perform these various processes.The instant system however, offers the further advantage that additionalfunctional stations can be added without a significant increase in sizeor without the need to add new total systems.

To achieve these various objectives, transport of wafers is structuredto be independent of chamber design. Thus the chambers are designed toperform as a chamber with certain processing capabilities and thetransport system is structured to operate independently of chamberdesign and is structured to feed wafers to and from processing chambers.Transport in the disclosed preferred embodiment is dependent on a simplelinkage arm based on linear and rotary motion coupled through a vacuumwall. In line with maintaining costs low, the chamber design is based onmodularity. Thus in one embodiment, the system may have 3 chambers or amatching structure can be utilized and the system can have 6 chambers.Alliteratively this last sentence can be repeated with 4 and 8 chambersas well as with other multiples, or modules may be matched that have adifferent number of processing stations.

The system is expandable and in addition it is expandable independentlyof technology that might be applied as future processes or applications.A linear wafer transport is used. This results in high throughput in asystem of small footprint that is not over demanding of space in cleanrooms. In addition different process steps can be structured into thesame treatment platform.

According to an aspect of the invention, a substrate processing systemis disclose, comprising an elongated substrate transfer chamber havingan evacuated section and an atmospheric section; a first linear trackaffixed to the transfer chamber within the evacuated section; a secondlinear track affixed to the transfer chamber at the atmospheric section;a first base linearly riding on the first linear track; a second baselinearly riding on the second linear track; a speed reducer mounted ontothe first base and having a magnetically-coupled follower as its inputand providing a lower rotational speed at its output; a rotary motormounted onto the second base and rotating a magnetic driver, themagnetic driver imparting a rotational motion to themagnetically-coupled follower across a vacuum partition; and, a robotarm coupled to the output of the speed reducer. A linear motor may beaffixed to the second base to impart linear motion, and magnetizedwheels may be coupled to the second base. A linear motion encoder may becoupled to the second base and a rotary encoder may be coupled to therotary motor. In a system having two robot arms, an arm extension may becoupled to one of the robot arm so as to enable the axis of rotation ofthe robot arms to coincide.

According to another aspect of the invention, a method for transferringwafers from a loadlock to a processing chamber via an evacuated transferchamber is provided, comprising: providing a robot arm within thetransfer chamber; magnetically coupling linear motion to the robot armacross a vacuum partition; magnetically coupling rotational motion tothe robot arm across a vacuum partition; and reducing the speed of therotational motion within the evacuated transfer chamber. The method mayfurther comprise the steps of: determining a first center point definedas the center of a wafer as it is located in the loadlock; determining asecond center point defined as the center of a wafer as it is located inthe processing chamber; determining location of a pivotal point of therobot arm; and, calculating a combination linear and rotational motionof the robot arm such that the wafer positioned on the robot arm movesin only straight lines between the loadlock and the processing chamber

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a prior art cluster tool intendedfor PVD applications.

FIG. 2 is a schematic illustration of the system described in theaforementioned patent publication (2006/0102078 A1) and is in the natureof a prior art system.

FIG. 3 is a schematic illustration of a processing system in accordancewith this invention.

FIG. 4 is a top schematic view for purposes of more clearly illustratingthe transfer chamber. In this Figure this has been done in a threeprocess station structure but this number of stations has been used onlyfor illustrative purposes.

FIG. 5 is a schematic view of a segment of the system from the load lockand into the transport or transfer chamber.

FIG. 6 is a schematic illustration of the wafer moving mechanism shownoutside the encasement for the system.

FIG. 7 is a schematic illustration of the track and drive systememployed in the preferred embodiment.

FIG. 7A illustrate an example of a linear motion assembly.

FIG. 7B is a sectional view about line A-A of FIG. 4, illustratinganother embodiment of the linear motion assembly.

FIG. 7C is a sectional view illustrating an example of a linear track inatmosphere and linear track in vacuum.

FIG. 7D illustrates another example of a linear track in atmosphere andlinear track in vacuum.

FIG. 8 is a schematic illustration of a 4-station physical vapordeposition (PVD) or sputtering system in accordance with this invention.

FIG. 9 is a schematic illustration of an 8-station system in accordancewith this invention.

FIG. 10 is a schematic illustration of a 6-chamber system in accordancewith this invention.

FIGS. 11A and 11B are schematic illustrations of two differentembodiments of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there is illustrated a cluster tool of the typecommonly in use today. In general this comprises processing chambers 21radially disposed around and attached to central chambers 22. In thissystem, there are two central chambers. Other systems may have only asingle central chamber. A system with more than two can exist exceptthat it is cumbersome and instead users will generally acquire anothersystem. In operation, a robot is typically located within each centralchamber 22. The robot receives wafers into the system and carries wafersfrom the central chamber to processing chambers and after processingback to the central chamber. In some prior art systems, a central robotcan access only a single wafer and single chamber at one time. Thus therobot can become engaged or busy during processing in connection while awafer is in a single chamber. This combination of a single robot tied toa processing station during processing is a limitation on the throughputof this type of cluster tool. More modern units use robotics that aremulti-armed. The processing chambers may comprise any form of processorand may comprise for example a chamber for physical vapor deposition, achamber for chemical vapor deposition (CVD) or for etch or for otherprocesses that may be performed on a wafer during its manufacture. Thistype tool permits processing for different periods of time since thetransfer by the robotic arm into the chamber and its removal from thechamber when the wafer is processed is independent of other factors andis computer controlled. Obviously processing can be set for the sametime and for a defined sequence.

Referring now to FIG. 2, there is illustrated a tool for processingwafers in which the dwell time of the wafer within a chamber is the samefor each chamber. In this embodiment the processors 23 are lined uplinearly and in this instance chambers are positioned adjacent to eachother and also on top of one another. At the end there is an elevator 25that moves the wafer being processed from one level to the other. At theentrance 26 a wafer enters and is positioned on a support where itremains as it moves through the system. In an embodiment of this system,the support raises the wafer to the upper level of processors and thewafer then moves in sequence one after the other through the processchambers 23 at that level. The elevator 25 changes the level of thewafer and it then moves along the other level, again from one processchamber through it and then through the next chamber and so on, and thenout of the system.

Referring now to FIG. 3, processing chambers 31 are located linearlyalong transport chamber 32. Wafers enter system 34 via EFEM (EquipmentFront End Module) 33 or some equivalent feeding device. EFEM 33comprises stations 30 upon which FOUP (from front opening unified pod)may be situated. The FOUPs (not shown) comprise a housing or enclosurewhere wafers are housed and kept clean while waiting to enter theprocessing operations. Associated with the EFEM 33 may also be a feedingmechanism to place wafers into the system for processing and to removewafers from the system to be temporarily stored after processing. A FOUPof wafers is placed onto the EFEM where wafers are then transferred oneby one from the FOUP by a blade that lifts the wafer from the FOUPwithin EFEM 33 and carries the wafer into load lock compartment 35 thusentering the system. From load lock compartment 35 wafers travel alongtransport chamber 32 from which they transfer into processing chambers31. After a substrate enters a processing chamber, the substrate leavesthe support arm and rests instead on a substrate support within thechamber. At this point a valve is closed to separate the atmosphere ofthe processing chamber from the atmosphere of the transport chamber.This permits changes to be made within the processing chamber withoutcontaminating the transport chamber or other processing chambers. Afterprocessing the valve separating the processing chamber from thetransport chamber opens and the wafer is removed from the processingchamber and transferred along transport chamber 32 to another processingchamber for additional processing or to the load lock from which thewafer is returned to FOUP on EFEM 33. In this Figure there are shown 4processing chambers 31. There is also shown 4 process power supplies 37and a power distribution unit 36. These in combination provide theelectronics for the system and the power to each individual processchamber. Above the process chambers 31 are process gas cabinets 38 andinformation processing cabinets 40. It is through these units thatinformation keyed into the system control movements of the substratesalong transport chamber 32 and whether or not the substrate istransferred into a processing chamber for further processing. Theseunits also provide records of what has occurred within the processingchambers. Gases are provided for use within the chambers duringprocessing. Although the robotic handling mechanism to feed wafers intothe system and through the processing stations in the system isdescribed as a two arm system, in fact more than two arms may be presentand each can be set to move independently or together within thetransport travel chamber.

The processing chambers in a system may perform different processes asdesired in the manufacture of wafers. Many manufacturers today buydedicated systems in which the entire system is given over to sputter oretch processes. In essence there are sufficient sputter steps or etchsteps in the manufacture of a wafer that a four or more stage system canbe entirely devoted to sputtering operations. Alternatively, a wafer canbe carried through a series of operations, each different yet eachrequired in leading to a final process. For example, in a five processstation, one could reasonably expect the following sequence in use. Atthe first process station the wafer will be subjected to a degasoperation; the second station could be a precleaning station; the thirda sputtering station to deposit titanium for example; the fourth asputter station to deposit nickel vanadium for example; and, at thefifth station the sputter deposition of gold could occur.

Referring now FIG. 4 there is illustrated a three station system withtop covers removed. An objective in connection with this Figure is toprovide more of an understanding of the transport chamber 32. A wafer tobe processed enters this system at load lock 35. Load lock 35 is a duallevel load lock and can hold and process two wafers simultaneously. Oneis on a lower lever and the other on an upper level. At the load lockwafers entering the system enter into the vacuum or controlledenvironment. Also wafers that have been processed pass through load lock35 during their travels leaving this system and the vacuum or othercontrolled conditions within the system and return into the FOUP (notshown in this Figure). Once a wafer completes its transition fromnon-vacuum conditions to vacuum conditions, the wafer is lifted onto anarm 41 which moves into transport chamber 32. One such arm is visiblewhile the other is partially covered by elements in the first processingchamber at the left. The visible arm is shown delivering a wafer intothis processing chamber 31 (or alternatively removing a wafer that hasbeen processed from this chamber). Arms 41 move along within thetransport chamber on a linear rail 43. In this embodiment the railswithin the transport chamber 32 hold the support arms 41 above the floorof chamber 32. Also, the driving mechanism, which is not seen in thisFigure, acts from outside the vacuum through the walls of the enclosureof chamber 32. It provides a generally linear movement to arms 41 aswell as a rotary movement when it is desired to extend an arm into achamber or into load lock 35. Thus the arms are used to move a waferinto or out of the transport chamber 32, into or out of a processingchamber 31 or into and out of load lock chamber 35. By avoiding contactwith the base of this chamber less particles are produced as to maintainthe environment in a purer or particle free condition. Additionaldetails of this transport system will be shown and discussed inconnection with figures that follow. Also although two arms areillustrated in this figure, it should be readily apparent that a systemcan have more or less than two arms on a rail and can handle more thantwo wafer transport devices at any one time.

According to a method of the subject invention, the support arms 41 areoperated using a combination of rotary and linear motion in a mannersuch that the wafer is moved in straight lines only. That is, as shownin FIG. 4, arm 41 is moved using a combination of linear motion,exemplified by double-head arrow A, and a rotary motion, exemplified bydouble-head arrow B. However, the motion is programmed so that thecenter of the wafer follows straight lines motion, as shown bybroken-lines BL1, BLm and BL. This enables making every opening ofchambers 31 and load lock 35 only slightly larger than the diameter ofthe chamber. This also enables attaching any type and any combination ofchambers onto transport chamber 32, as the combined linear-arcuatemotion of the arms 41 is actuated by a controller that can beprogrammed, e.g., via user interface UI (FIG. 3) to any situation.

According to a method of the invention, the following process isimplemented to calculate the combined linear-arcuate arms' motionexecuted by the controller. The location of the center of a wafer as itis located in the loadlock is determined. The center of a wafer as it islocated inside each of the attached processing chambers is determined.The pivotal point of each arm is determined (note that as discussedbelow, in some embodiments the pivotal points of both arms may be madeto coincide). The order of transport is determined, i.e., whether eachwafer needs to move between the loadlock and only one or more chambers.These values can be programmed into the controller using the UI. Then,the linear and rotational motion of each arm is calculated such that awafer positioned on each arm would move in only straight lines betweenthe determined pivotal point and the center determined for the loadlockand the chambers.

Partly in order to simplify the combined linear-arcuate motion of thearms 41, the following feature of the invention is implemented in oneembodiment. In FIG. 4, one of the support arms 41, specifically the arm41 that is fully exposed in FIG. 4, is coupled to an arm extension 41′,while the other arm 41 is coupled directly to the internal drive andsupport mechanism 45 (see also FIGS. 5 and 6). In the embodimentillustrated, the arm extension 41′ is fixed, i.e., it only follows thelinear motion of the drive and support mechanism 45, but it cannot berotated. Rather, rotational motion is only imparted to the arm 41affixed to the end of the arm extension 41′. Also, in the embodimentillustrated, the arm extension 41′ is affixed such that the center ofrotation or pivotal point of both arms 41 may be made to coincide, i.e.,as shown the straight broken line BLm passes through the center ofrotation or pivotal point of both arms 41. Moreover, as shown in theembodiment of FIG. 5, the arms 41 may be moved in linear direction suchthat the center of rotation of both arms 41 exactly coincides one abovethe other. Such a design allows fabricating the two arms 41 to beidentical, as they will follow the same combined linear-arcuate motionfrom the same pivotal point centerline.

Referring now to FIG. 5, this figure shows portions of system 34,without covers closing off the internal elements, starting at load lock35, continuing into the beginning of transport chamber 32 and includinga first processing chamber 31. Illustrated in this figure a wafer 42 inload lock 35 rests on arm 41. Another arm 41 is shown extended intoprocess chamber 31. As shown the arms, which act independently and maybe at different levels, can be extended into different areas at the sametime. The arms move wafers along transport chamber 32 into the systemfrom the load lock and then about the system from processing chamber toprocessing chamber. Eventually the arms move the wafers after processingalong the transport chamber and into load lock 35 and then out of system34. When processing is completed, the wafer may then pass back into theFOUP from the load lock where processed wafers are collected. A wafer inthe load lock or in process chambers is transferred by being lifted on asupport surface associated with arm 41. Lift pins at the support surfaceraise the wafer to allow the arm access below the wafer permitting thearm to lift the wafer and move the wafer for next steps in the system.Alternatively, a structure in the nature of a shelf to slide under thewafer and support the wafer during transport may be employed to supportand hold the wafer and to accept and release wafers from arms 41 whenbrought or taken from a chamber or compartment. The arms are positionedto pass above and below each other without contact and can pass by eachother. They are connected to an internal drive and support mechanism 45.Drive and support mechanism 45 is provided with a linear drive trackalong which drive and support mechanism travels within transport chamber32. Movement of drive and support mechanism 45 is brought about by anexternal driver such as a motor. One form of drive causes drive andsupport mechanism 45 to move linearly along drive track 46. Anothercause's rotation of arms 41 to extend them from the transport chamber 32into load lock 35 or process chambers 31 in the course of moving a wafer42 into and through the system. Within drive track 46 are individualrails 47 (rails 47 are more clearly shown in FIG. 6) on which each driveand support mechanism independently rides enabling positioning so thateach arm 41 moves and acts independently of the other. Movement of thewafer into a process chamber is in the nature of translating from itslinear drive path into the chamber. This occurs because the wafer isundergoing two forms of motion simultaneously in the preferredembodiment. It is being moved linearly and rotated at the same time. Theuse of external motors or other forms of drive mechanism to drive thismechanism within the vacuum of transport chamber 32 reduces unwantedparticles within the enclosed vacuum area.

Referring now to FIG. 6, there is illustrated the driving systememployed in the preferred embodiment of this invention. In this figure,rails 47 of drive track 46 are each independently viewable. There isalso shown a wafer 42 on one of the support arms 41. The other supportarm is simply shown extended in this figure. Drive and support mechanism45, each ride on one of rails 47. This facilitates the positioning ofthe arms 41 at different levels. Positioned at the base of each of thedrive and support mechanism 45 is a magnetic head ormagnetically-coupled follower 48. Positioned spaced from magnetic head48 is a magnetic driver 50. Magnetic heads 48 are positioned within thevacuum of the transport chamber and a wall of the vacuum chamber (shownas 53 in FIG. 7) passes beneath each of the magnetic heads 48 andbetween the magnetic heads 48 and drivers 50. Thus drivers 50 areoutside the vacuum wall of transport chamber 32. As has been discussed,arms 41 move wafers 42 into and through the processing system and arms41 move independently of one another. These arms 41 are driven by amagnetic coupler arrangement comprising driver 50 and magnetic head 48.The coupler imparts both linear and rotary motion to arms 41. Driver 50rides on outer rails 51 which are located outside the vacuum and appearon both sides of the rail system. One set is seen in a facingrelationship while another exact rail appears on the opposite side.Rotation of the arm is transferred through the magnetic couplers and isdriven by rotary motors 52. Although magnetic coupling is illustrated asused for linear movement and for rotation in this figure, it should bereadily apparent that separate magnetic couplers and drivers may beused. Thus, although it is preferred to transfer linear and rotationalmovement through the same couplers, it is also possible to use separatecouplers for linear movement and another set for rotational motion.

One type of arm that may be used to move and manipulate the wafersthrough transport chamber 32 including stops at the process stations 31is described as a selective compliant articulated assembly robotic arm,referred to in a shorthand way as a SCARA robot. A SCARA system tends tobe faster and cleaner than the Cartesian system it would likely replace.

Also in order to reduce and/or eliminate load factors in connection withthe magnetic drive system, one can include repulsing magnets that willreduce the attractive forces created by the motion coupling magnets. Themagnets that couple the rotary and linear motion into the vacuum have asignificant amount of attractive force. This loads the mechanicalmechanism that supports the parts. High loads mean lower bearing lifeand more particle generation. By using magnets located in the magneticcouplers or in a separate arrangement that repulse each other theattractive force can be reduced. In fact, inside the magnetic couplerthe inner most magnets are not significant in achieving couplingstiffness. These inner magnets can however, be used to create arepulsive force with the coupling magnets used in attraction disposed inalternating N-S positions around the diameter of the coupler.

It should be understood of course that if one is not concerned aboutparticle dust within the enclosed chambers, then drive mechanism may beincluded within the enclosed chambers.

Referring now to FIG. 7, there is shown a side view, without cover, ofthe track and drive system. In this figure, the vacuum wall or vacuumpartition 53 is illustrated in its position between magnetic couplers 48and 50 that drive and control the position of arms 41. Drive track 46encloses rails 47 which provide linear motion imparted by outer rails 51to drive and support mechanism 45 and thus to arms 41. Rotational motionis imparted by rotary motors 52. In FIG. 7, the side marked Va is invacuum, while the side marked At is in atmosphere. As shown in FIG. 7,magnetic coupler 50 is driven by rotary motor 52, and causes coupler 48to follow the same rotational motion due to magnetic coupling acrossvacuum partition 53. However, due to hysteresis in the magneticcoupling, the accuracy of the rotational motion of the arm may bedegraded. In fact, due to the length of the arm, a small angular errorin the couplers 48-50 may lead to a large displacement of the wafer thatsits at the end of the arm 41. Also, due to the length and weight of thearm, and changes in weight depending on whether the arm supports a waferor not, transient motions may persist for an unacceptable length oftime. To avoid these problems, a reducing gear (sometimes referred to asspeed reducer or gear reducer) 55 is interposed between the coupler 48and the rotation coupler 56 or arm 41. The gear reducer 55 has its inputthe rotation of the magnetic coupler 48, and provides an output at aslower rotational speed so as to actuate the arm 41 at a rotationalspeed that is lower than the rotational speed of motor 52. In thisparticular example, the gear reducer is set to a reducing ratio of 50:1.This drastically increases the accuracy of the angular placement of thearm 41, reduces transient motion, and reduces the moment of inertia ofthe art on the drive assembly.

In FIG. 7 the reducing gear assembly 55 is mounted onto base 49. Base 49is unmotorized and rides freely on linear rails 47. On the other hand,rotary motor 52 is mounted onto base 54, which rides on linear rails 51using mechanized motive power. As the mechanized motive power linearlymoves base 54, the magnetic coupling between the magnetic coupler 50 andmagnetic follower 48 imparts the linear motion to the free riding base49, thereby linearly moving the arm 41. Consequently, this arrangementis advantageous in that all of the motorized motions, i.e., linear androtational, are performed in atmospheric conditions, while no motorizedsystem resides inside the vacuum environment. Various embodiments forthe motorized motion in atmosphere and the free-unmotorized motion invacuum are described below as examples.

FIG. 7A illustrates an example of linear motion assembly. In FIG. 7A, abelt or chain drive is coupled to a base 54. The belt or chain 58 rideson rotators 59, one of which is motorized so as to impart motion ineither direction, as illustrated by arrow C. To control the linearmotion, an encoder 57 a sends signals to a controller identifying thelinear motion of base 54. For example, the encoder 57 a may be anoptical encoder reading encoding provided on linear track 46.Additionally, a rotary encoder 47 b is provided on motor 52 and alsosends encoding of the rotational motion to the controller. Thesereadings of rotary and linear motion may be used to control therotational and linear motion of the arms 41, such that the centerline ofthe wafer is moved only in straight lines.

FIG. 7B is a sectional view about line A-A of FIG. 4, illustratinganother embodiment of the linear motion assembly. In FIG. 7C, drivetrack 46 supports rails 47, upon which wheels 61 and 62 ride. Thesewheels may be magnetized to provide improved traction. The wheels 61, 62are coupled to the base 54, upon which the rotary motor 52 is mounted. Alinear motor 63 is mounted to the lower part of the base 54 andinteracts with an array of magnets 64 that are mounted onto the drivetrack 46. The linear motor 63 interacts with magnets 64 to impart alinear motive force to move the base 54 in the direction in and out ofthe page. The linear motion of the base 54 is monitored and reported byencoder 57 b, which reads position/motion encoding 57 c provided on thetrack 46. In this specific example, the encoder 57 b has a precision offive-thousands of an inch.

FIG. 7C is a sectional view illustrating an example of a linear track inatmosphere and linear track in vacuum. The vacuum side is indicated byVA, while the atmospheric side is marked by AT, and vacuum partition 53together with the chamber wall 32, separates between the two sides. Inthe atmospheric side, riders 61 ride on linear tracks 47. Since thisside is in atmosphere, particle generation is not as important as in thevacuum side. Therefore, riders 61 may include wheels or may simply bemade of sliding material, such as teflon. The base 54 attaches to thesliders 61 and supports the rotary motor that rotates the magneticcoupler 50. On the vacuum side, linear tracks 78 are made to acceptsliding bearings 73, which are attached to base 70 via coupler 72. Thesemay be made of stainless steel and should be fabricated to minimizeparticle generation. Additionally, covers 74 and 76 are provided inorder to keep any particles generated within the confines of the bearingassembly. The base 70 extends beyond the bearing assembly and supportsthe gear reducer 55, which is coupled to the magnetic follower 48.

FIG. 7D illustrates another example of a linear track in atmosphere andlinear track in vacuum. In FIG. 7D the atmospheric side may beconstructed the same as that of FIG. 7C. However, in order to minimizecontamination, in the vacuum side magnetic levitation is utilizedinstead of slider bearings. As illustrated in FIG. 7D, activeelectromagnetic assemblies 80 cooperate with permanent magnets 82 toform magnetic levitation and allow free linear movement of base 70.Notably, the permanent magnets 82 maintain free space 84 and do notcontact electromagnet assemblies 80. As base 54 moves linearly withsliders 61, magnetic coupling between coupler 50 and follower 48 impartthe linear motion to the levitated base 70. Similarly, rotation of thecoupler 50 causes rotation of the follower 48, which transmits therotation to gear reducer 55.

Referring now to FIG. 8 there is illustrated a processing system inaccordance with this invention. As in the case of FIG. 3, EFEM 33receives and stores wafers for presentation to system 34 includingprocess chambers 31, which in this embodiment are intended to illustratechambers in which sputter deposition occurs, by transferring the wafersfirst to load lock 35 and then along transport or transfer chamber 32.Processed wafers are then fed back along transfer chamber 32 to loadlock 35 and then out of the system to EFEM 33.

Referring now to FIG. 9 there is illustrated an eight station processingsystem in accordance with this invention. EFEM 33 feeds wafers to loadlocks 35. Wafers are then moved along transport chambers 32 and fromtransport chambers 32 into processing chambers 31. In this figure bothsets of transport chambers are positioned in the central area and theprocess chambers 31 are on the outer sides. In FIG. 10 the processingsections are all lined up so that one set of processing chambers is aduplicate of the next set. Thus the processing chambers of the systemappear lined up in parallel.

Other variations are readily possible and easily conceived. For example,instead of lining up the processing chambers as shown in FIGS. 9 and 10,processing chambers could be positioned one set above another or one setfollowing another. If aligned with one set following another, the setscan be lined up so that the second set continues in line following thefirst set or alternatively the second set can be set at some form ofangle to the first set. Since a transport chamber can feed wafers toeach side of the chamber, two sets of processors can be set around asingle transport chamber and fed by the same transport chamber (see FIG.11A where numbers designate the same items as were discussed inconnection with earlier figures. It is noted that added to FIGS. 11A and11B is a showing of the valve 39 that separates the processing chambers31 from the transport chambers 32 as has been discussed above.) If thesecond set of processors is a continuation of the first set there cansometimes be benefits to positioning additional load locks along thesystem. It is of course possible to add an EFEM at the far end andposition a load lock before the EFEM so that the wafer can travel in astraight line entering at one end and leaving at the other (see FIG.11B, where again numbers designate the same item as in earlier figures).In this latter case, the wafer can be programmed to enter or leave ateither or both end(s). It is also possible to position processingchambers along the transfer chamber at irregular intervals or withspacing between the processing chambers. In this arrangement the keyfeature will be the positioning of the transfer chamber so that it canfeed wafers to the individual processing chambers as desired and asdirected by the computer controls for the system.

Although the chambers have been described as under vacuum conditions, infact in some instances there can be benefits to including certain gasesor other fluids in the contained areas. Accordingly the term vacuum asused herein should also be interpreted as a self contained environmentas to encompass special gases for example that may be employed in thetotal system.

In FIG. 1, the cluster tool includes 7 processing chambers. In FIG. 9the disclosed system includes 8 processing chambers. The total footprintof the tool in FIG. 1 with peripherals is approximately 38 m². The totalfootprint of the tool in FIG. 9 (with an additional processing chamberand peripherals) is 23 m². Thus the footprint for a system with morechambers is considerably less if a linear arrangement in accordance withthis invention is employed. In large measure this improvement isachieved through the use of an improved feed system illustrated astransport chamber 32 in FIG. 9 as compared to the use of centralsections as is done with the system of the type shown in FIG. 1.

The linear architecture of the present invention is extremely flexibleand lends itself to multiple substrate sizes and shapes. Wafers usedinto the fabrication of semiconductors are typically round and about 200or 300 mm in diameter. The semiconductor industry is always trying toget more devices per wafer and has steadily moved to larger and largerwafer sizes from 75 mm, 100 mm, 200 mm to 300 mm and there is an ongoing effort to look at moving to 450 mm diameter wafers. Due to theunique architecture the floor space required in the clean room wafer fabwould not grow as large as it would with a typical cluster tool with theprocesses located on the circumference.

Further if it is desired to increase the size of the cluster tool type(FIG. 1) to increase output, the add on to the total measurements is toa raised power; whereas, an increase in size of the system described inthis application is in a single direction, i.e., length, with the widthof the system staying the same. In similar processes, such as analuminum process, throughput for the same period of time using thesystem of the type illustrated in FIG. 9, which occupies less space thanthe equipment shown in FIG. 1, the equipment of FIG. 9 produces almosttwice as many wafers (in quick calculations about 170%) as does a systemlike that of FIG. 1. Thus there is a considerable improvement in waferoutput per a measured clean room area using the system disclosed ascompared to prior art units. Obviously this achieves an objective ofreducing costs in the manufacture of wafers.

The design of this equipment is not limited to circular substrates. Acluster tool that moves wafers in paths described by arcs isparticularly disadvantaged if the substrates are rectangular as the toolwould need to be sized to handle a circular substrate that inscribes therectangular shape of the actual substrate; whereas, the linear tool needbe no larger in any direction than what is required to pass the actualshape. For example, working with a 300 mm square substrate, a clustertool would need to be sized to handle a 424 mm circular substrate whilethe linear tool need be no larger than that required for a 300 mmcircular substrate.

Also the size of the transport chamber 32 need provide only that roomrequired to move the substrate whether a wafer of some other member,along from the entrance chamber through and into processing chambers andfrom processing chambers out of the system. Thus the width of thischamber should be slightly larger than the size of the substrate to beprocessed. However, smaller members may be processed in the system, andmay be processed together as a plurality in a substrate holder.

While this invention has been discussed in terms of exemplaryembodiments of specific materials, and specific steps, it should beunderstood by those skilled in the art that variations of these specificexamples may be made and/or used and that such structures and methodswill follow from the understanding imparted by the practices describedand illustrated as well as the discussions of operations as tofacilitate modifications that may be made without departing from thescope of the invention defined by the appended claims.

1. A substrate processing system, comprising: an elongated substratetransfer chamber having an evacuated section and an atmospheric section;a first linear track affixed to the transfer chamber within theevacuated section; a second linear track affixed to the transfer chamberat the atmospheric section; a first base linearly riding on the firstlinear track; a second base linearly riding on the second linear track;a speed reducer mounted onto the first base and having amagnetically-coupled follower as its input and providing a slowerrotational speed at its output; a rotary motor mounted onto the secondbase and rotating a magnetic driver, the magnetic driver imparting arotational motion to the magnetically-coupled follower across a vacuumpartition; and, a robot arm coupled to the output of the speed reducer.2. The substrate processing system in accordance with claim 1, furthercomprising a linear motor affixed to the second base.
 3. The substrateprocessing system in accordance with claim 2, further comprising alinear motion encoder coupled to the second base and a rotary encodercoupled to the rotary motor.
 4. The substrate processing system inaccordance with claim 3, further comprising magnetized wheels coupled tothe second base.
 5. The substrate processing system in accordance withclaim 1, further comprising: a third base linearly riding on the firstlinear track; a fourth base linearly riding on the second linear track;a second speed reducer mounted onto the third base and having a secondmagnetically-coupled follower as its input and providing a lowerrotational speed at its output; a second rotary motor mounted onto thefourth base and rotating a second magnetic driver, the second magneticdriver imparting a rotational motion to the second magnetically-coupledfollower across a second vacuum partition; and, a second robot armcoupled to the output of the second speed reducer.
 6. The substrateprocessing system in accordance with claim 5, further comprising an armextension coupled between the robot arm and the speed reducer so as toenable the axis of rotation of the robot arm and the axis of rotation ofthe second robot arm to coincide.
 7. The substrate processing system inaccordance with claim 1, wherein the first linear track comprisesmagnetic livitation assembly.
 8. A substrate processing system,comprising: an elongated substrate transfer chamber having an evacuatedsection and an atmospheric section; a first linear track affixed to thetransfer chamber within the evacuated section; a second linear trackaffixed to the transfer chamber at the atmospheric section; anunmotorized base freely riding on the first linear track; a motorizedbase linearly riding on the second linear track; a speed reducer mountedonto the unmotorized base and having a magnetically-coupled follower asits input and providing a slower rotational speed at its output; arotary motor mounted onto the motorized base and rotating a magneticdriver, the magnetic driver imparting a rotational motion to themagnetically-coupled follower across a vacuum partition; and, a robotarm coupled to the output of the speed reducer.
 9. The substrateprocessing system in accordance with claim 8, further comprising: a loadlock opening; a plurality of processing chambers openings; and, acontroller programmed to actuate the motorized base and rotary motor ina combination of linear and rotational motions such that a substratepositioned on the robot arm moves in only straight lines between theload lock opening and the processing chambers openings.
 10. Thesubstrate processing system in accordance with claim 8, wherein themotorized base comprises a linear motor.
 11. The substrate processingsystem in accordance with claim 8, wherein the unmotorized basecomprises magnetic levitation arrangement.
 12. The substrate processingsystem in accordance with claim 10, further comprising a linear motionencoder coupled to the motorized base and a rotary encoder coupled tothe rotary motor.
 13. The substrate processing system in accordance withclaim 8, further comprising: a second unmotorized base linearly ridingon the first linear track; a second motorized base linearly riding onthe second linear track; a second speed reducer mounted onto the secondunmotorized base and having a second magnetically-coupled follower asits input and providing a slower rotational speed at its output; asecond rotary motor mounted onto the second motorized base and rotatinga second magnetic driver, the second magnetic driver imparting arotational motion to the second magnetically-coupled follower across asecond vacuum partition; and, a second robot arm coupled to the outputof the second speed reducer.
 14. The substrate processing system inaccordance with claim 13, wherein the second robot arm is coupled to thesecond speed reducer such that it may linearly pass below the robot arm.15. The substrate processing system in accordance with claim 14, whereinwhen the second robot arm is situated below the robot arm, therotational axis of the robot arm and the second robot arm coincide. 16.The substrate processing system in accordance with claim 13, furthercomprising an arm extension coupled between the second robot arm and thesecond speed reducer such that the second robot arm may linearly passabove the robot arm.
 17. The substrate processing system in accordancewith claim 16, wherein the arm extension is fixed and not movable.
 18. Amethod for transferring wafers from a loadlock to a processing chambervia an evacuated transfer chamber, comprising: providing a robot armwithin the transfer chamber; magnetically coupling linear motion to therobot arm across a vacuum partition; magnetically coupling rotationalmotion to the robot arm across a vacuum partition; reducing the speed ofthe rotational motion within the evacuated transfer chamber.
 19. Themethod of claim 18, further comprising: determining a first center pointdefined as the center of a wafer as it is located in the loadlock;determining a second center point defined as the center of a wafer as itis located in the processing chamber; determining location of a pivotalpoint of the robot arm; and, calculating a combination linear androtational motion of the robot arm such that the wafer positioned on therobot arm moves in only straight lines between the loadlock and theprocessing chamber.